Unit of Direct IO LOB and Unit of Add LOB Data Log Record should match? Implication on Recovery of LOB Object?
I have a recoverable database with logged LOB column of 4 MB in
a table. Import one record inserting data into that LOB column.
IBM KC clearly states that Insert of one LOB object is split into multiple Add LOB Data Log Record with some portion of actual LOB data in case it is logged LOB column.
This is obviously used for recovery purposes or replication purposes.
KC also mentions elsewhere that LOB data is written into Tablespace containers in hard disk without using bufferpools.
So the question is Amount of LOB data written into Log Records should match the DATA IO size written into containers?
My thinking is it should match,otherwise more data might be written into the disk and less data being written into containers might not go well in terms of roll forward at a later point in time.
Even crash recovery involving LOB data might rollback large amount of data from disk because of this mismatch in LOB Data Size being written.
Obviously i am doing a lot of test cases and trying to come up
with a number with snap shot monitoring. It is going to take some
But conceptually i need to ask how db2 is handling it in the first place.
Any Inputs help will bring significant amount of clarity in managing LOB objects on different IO devices [LOG IO and HARD Disk IO].